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The Shaughnessy Report: Zee Plane! Zee Plane!

We have a lot of fun with our cover images, but of course, we’re really here to talk about power and ground planes, not the flying kind. These planes don’t carry human passengers, but they do help your signals get to their final destination in today’s PCBs.

Planes aren’t magic, but they are big time-savers. Without planes, designers would have to create thousands of traces to accomplish the same objectives. You can imagine the first time a designer thought about using a sheet of copper, asking, “Hey, why am I killing myself laying out all these traces? Can’t I just use this sheet of copper instead?”

However, planes are more than simple copper pours. They provide a decisive advantage in that they have extremely low impedance: Since it’s a sheet of copper, the impedance is almost non-existent.

As a result, power planes provide low impedance and stable power to every component on the board, much like a large power bus. Next to a signal layer, a power plane can shield signals and stop crosstalk and noise. They make great heat sinks too.

Ground planes stabilize reference voltage, improve thermal performance, and help preclude EMI issues. They offer a low-impedance return path, which helps eliminate jitter and reflections.

Power and ground plane design is often a battle of tradeoffs. Selecting the correct copper thickness of power planes is a good example: Thin copper with high currents can cause IR drop, which can lead to timing errors. This can be mitigated by using thicker copper, but this also affects your signal integrity planning, not to mention your fabricator’s workload.

Speaking of fabricators, keep your CAM partners in the “loop area” when you’re designing your power and ground planes. They can help you find the perfect trade-offs between performance and cost, avoiding both scrap and overspecifying a costly PCB.

The latest simulation tools can help, but designing planes is becoming increasingly complicated as we move further into technologies such as EVs, 5G, and AI. Incorrect plane design can lead to catastrophic failures and a variety of manufacturing defects.

This month, our expert contributors, including Kirk Fabbri of Siemens EDA, John Watson of Palomar College, and Barry Olney of In-Circuit Design, discuss the best practices for designing power and ground planes, along with the many electrical and manufacturing tradeoffs that can trip up PCB designers. We also have columns by Kelly Dack and Matt Stevenson, and an article by Anaya Vardya.

This column originally appeared in the November 2025 issue of Design007 Magazine.